Healthcare-associated infections are infections that patients acquire during the course of receiving healthcare treatment for other conditions. They are a significant hazard for patients, and health care workers are potential sources of these infections which are a significant cause of morbidity, mortality, and increased cost. Reported incidence of these infections is as high as 15.5% of hospitalized patients in some series. Hospital environment likely acts as a reservoir for the potential pathogens. The natural history of the development of hospital-acquired infections appears to begin with exposure of patients to pathogenic bacteria which have colonized hospital equipment, or skin and nasopharynx of hospital personnel. Subsequently, colonization of the patients' skin, gut, or systems with hospital flora occurs; infections ensue when the normal body defenses are impaired through underlying diseases, administration of immunomodulating therapy or use of invasive devices.
While many of the pathogens can be transmitted by hand carriage, there are mechanisms in place to address this issue, such as hospital-wide incentives reminding health care workers to wash hands before and after seeing each patient, or conveniently available hand sanitizers in each patient room which make it easy to minimize these transmissions. However, transmission of infections through contaminated medical devices such as stethoscopes has also been demonstrated, and studies show that they can harbor various organisms on their diaphragm surfaces. Following contact with infected skin, pathogens can attach and establish themselves on the diaphragms of stethoscopes and subsequently be transmitted to other patients during routine physical examination.
Contaminants that have been well documented on stethoscope surfaces include coagulase negative staphylococci, Staphylococcus aureus, Corynebacterium spp., Bacillus spp., Neisseria spp., alpha-hemolytic streptococci, Micrococcus luteus, Enterococcus spp., Candida spp., Gram negative organisms (including Pseudomonas aureginosa; also non-fermenting gram negative bacilli, including Acinetobacter spp. and Stenotrophomanas maltophilia, both of which are of increasing importance as causes of multi-drug resistant infections in immune-compromised hospital patients), Enterococcus faecalis, Escherichia coli and Aspergillus spp. Point-prevalence culture surveys have also demonstrated that stethoscope diaphragms may be contaminated with pathogens such as Clostridium difficile. Also, it is known that several common viruses (e.g. enteroviruses and small round structured viruses) survive well in the environment and may be transmitted by fomites on stethoscope surfaces. Norovirus has been shown on hospital surfaces as well and could likely be transmitted via stethoscopes.
In addition to a wide variety of organisms that have been shown to contaminate stethoscope surfaces, the sheer prevalence of such contamination is stunning; at least one organism has been demonstrated in 79% to 100% of stethoscope surfaces surveyed in various series.
The hands of healthcare workers may well represent the final mode of transmission as it appears that sites frequently touched by hands are thought to provide the greatest risk for patients. For example, there seems to be a link between Staphylococcus aureus nasal carriage and staphylococcal infection; a causal relation between carriage and an infecting strain is shown by the fact that the nasal strain of Staphylococcus aureus and the infecting strain share the same genotype. Given the propensity for people to pick, touch, or blow their noses, it is not surprising that carriers will often harbor their own strain of Staphylococcus aureus on their fingers, which they will then transfer to any site accessible to their hands. This likely applies to transmission of pathogens from all the surfaces that health care workers touch on a routine basis, including contaminants among different patients. We may think then that maintaining good hand hygiene is enough to prevent these hospital-acquired infections. However, even exemplary hand hygiene cannot be expected to break the chain of infection when the environment is heavily contaminated. If a health care worker uses wall-mounted hand disinfectant prior to and after each patient contact but they do not disinfect their stethoscope routinely, then their clean hands will become contaminated from touching the dirty stethoscopes again and will potentially contaminate the patients anyway. It follows that anything that depends on hands for functionality is at risk of contamination from a carrier's strain, even if hands are disinfected. As even short periods of contact between a patient's skin and the stethoscope can result in transfer of bacteria, there is a need for strategies to decrease bacterial contamination of stethoscopes and strict adherence to stethoscope disinfection practices by health workers will minimize cross-contamination and ensure improved patient safety in hospitals.
An obvious risk of lack of stethoscope disinfection practices is dissemination of multi-resistant organisms. There are increasing reports of these organisms being transmitted via stethoscope surfaces, capable of initiating severe infections in a hospital environment, which may require contact isolation. Patients with open wounds, such as those with burns or tracheotomies, may be colonized leading to infection at a later time.
Multiple studies demonstrated that enhanced cleaning of clinical equipment and other inanimate near-patient sites is an effective mechanism of reducing MRSA, Clostridium difficile, and Norovirus infections. Specifically, cleaning the stethoscope diaphragm has been shown to result in immediate reduction of bacterial contamination on its surface. In order to be effective, decontamination would have to be performed after each use of the stethoscope. Unfortunately, despite this wide array of pathogenic organisms that could be spread among patients and evidence that disinfection may decrease contamination, studies show that routine disinfection of stethoscopes in between patients and before each patient contact is not an established practice and according to some studies it is hardly ever undertaken. Multiple studies confirm that surveyed physicians and other health care professionals rarely clean their stethoscopes on a regular basis. In one series, 40% of health care workers studied did not clean their stethoscopes at all, while among the ones who did, frequency of cleaning was only monthly to yearly. The same studies report lack of guidelines or advise being given to personnel on how or how regularly to disinfect stethoscopes. As low as 0-3% of health-care providers clean their stethoscopes regularly in other series, and just 10% cleaned them when they were soiled with blood or human secretions.
The importance of routine disinfection of stethoscopes before each and every patient contact cannot be emphasized enough. A study that examined transfer of organisms from patients to stethoscope surfaces in a series of patients demonstrated than when a sterilized stethoscope (as evidenced by negative culture of the diaphragm after disinfection) is applied to only one patient's chest, in 57% of cases stethoscopes grew Staphylococcus aureus. There is a statistically significant correlation between the mean number of staphylococcal CFUs (colony forming units) grown from stethoscope surfaces and periods of time in between cleanings—specifically, there is a marked increased in mean CFUs as the stethoscopes went for longer periods of time in between cleanings. The highest levels of bacterial contamination were found on stethoscopes that had never been cleaned.
Strict adherence to stethoscope disinfection practices by health workers can minimize cross-contamination and ensure improved patient safety in hospital environment. Studies support the necessity for clear disinfecting guidelines, outlining the need to disinfect stethoscopes before and after every patient contact in order to limit the bacterial load to which patients are exposed. However, currently available methods involving alcohol or bleach wipes are cumbersome, time consuming, and inconvenient; many times, alcohol wipes are not even available immediately upon entrance to a patient's room. These factors likely account for such a low compliance rates, given that convenience and availability appear to determine the method of stethoscope disinfection used by health care professionals.
Strategies to minimize the transmission of infection from stethoscopes have been proposed, including the use of disposable stethoscopes, especially for clinical high-risk environments, and the use of a single-use, membrane cover over the stethoscope head to create a prophylactic barrier. Although these strategies could minimize the risk of stethoscope transmission of infections, they are unlikely to be cost-effective in developing countries, and even in developed countries where they can be easily obtained, they remain cumbersome and inconvenient, adding more steps for healthcare workers to follow, in turn resulting in lower rates of compliance.
Numerous portable stethoscopes cleaning devices exist. For example, Cleanstethoscope by Cleanint offers a stethoscope cleaning device comprising a holder for an insertable sponge-like insert. The insert comprises a proprietary, alcohol-free cleaning solution. When not in use, the care-provider places the diaphragm into the holder where it is in contact with the sponge and the cleaning solution.
Although, small and compact, this device has several potential limitations and disadvantages. For example, germs and spores that are removed from the diaphragm surface will remain in the sponge, and may potentially be reintroduced onto the stethoscope during the next use and transmitted to subsequent patients. In addition, this device requires the user to carry replacement sponges, making the system potentially inconvenient, resulting in the care-provider being less likely to replace them with the frequency needed for the system to be most effective. Also, a care-provider needs to touch the product with their hands, to place the sponges in the holder. Also, if the user does not pay close attention to the freshness of the sponge, they may end up using the dry sponge many times over before it is replaced with a fresh one, causing even more contamination than not using it at all. So, unless gloves are strictly worn 100% of the time when using the stethoscope and when replacing sponges, contamination may result. Since, it is suggested that his system be worn on a care-giver's lab coat, the lab coat itself may become contaminated as a result of using of the device.
U.S. Pat. No. 7,360,625 to Stickley (“Stickley”) discloses another stethoscope sanitizing device that is connected directly to the stethoscope. When the stethoscope is not being used, the device covers the diaphragm and bell portions with sanitizing pads. When the care-giver wishes to use the stethoscope, the device is slid up a length of the stethoscope to expose the diaphragm for use. This device appears to have some of the same potential disadvantages as the Cleanstethoscope device, including the accumulation of contamination in the cleaning device itself over time, and accidental contamination of other parts of the stethoscope as well as the care-giver's clothing. Also, carrying extra weight is likely to result in discomfort for the provider, which would likely lead to poor compliance. Another device with similar features and disadvantages is disclosed in PCT Patent Application Publication No. WO 2010/131253 to Nahman et al. (“Nahman”). Stickley and Nahman are incorporated by reference in their entirety for all purposes.
U.S. Pat. No. 7,705,325 to Vestal (“Vestal”) discloses a stethoscope sterilization device, also mounted on the stethoscope itself. In this case the device comprises a cover member and an ultraviolet light source. The ultraviolet (UV) light source is operably engaged with the cover member and configured to emit ultraviolet radiation for interacting with the face portion of the stethoscope only when the cover member is covering the stethoscope's face portion. However, there are potential disadvantages to this system, too. Even though studies demonstrate that UV light can be effective in disinfecting surfaces, this is typically done in controlled laboratory environment, using high power UV light for long periods of time, which do not necessarily replicate the “in-use” conditions. In addition, the presence of organic matter on surfaces reduces the efficacy of UV radiation in killing C. difficile spores, necessitating the combined use of some mechanical cleaning means for removing the organic matter, film, or coating. Again, this type of system leads to the issue of extra weight that needs to be carried around by the care-giver. Vestal is incorporated by reference in entirety for all purposes.
Canadian Patent No. 2,440,636 to Giroux et al. (“Giroux”) discloses a protective sleeve cartridge that is located on the stethoscope head itself. The cartridge contains a plurality of longitudinally connected sleeves, separated by perforations. With each use, the care-giver uses a new sleeve to cover the stethoscope diaphragm, thus avoiding direct contact with the patient's skin. Once finished with the examination, the care-giver discards the used sleeve, and covers the stethoscope with a new one. This system also has some potential disadvantages. First, although this system may minimize contact of the stethoscope with the patient, it does nothing to actually clean and/or disinfect the stethoscope. In addition, attaching this system to the stethoscope appears to require some dexterity to properly cover the stethoscope. Finally, accidental contamination of the sleeve seems likely, which in turn, can lead to subsequent accidental contamination. Giroux is incorporated by reference in entirety for all purposes.
Therefore, and in light of CDC statistics that show that 1 in 20 hospitalized patients will contract a hospital-acquired infection, and considering the fact that the annual cost of hospital-acquired infections in the US ranges up to $45 billion according to some estimates, there is a clear need for improved devices and methods for cleaning stethoscopes, in addition to cleaning other commonly used medical devices that are placed in contact with a patient's skin, to prevent or reduce the frequency of hospital-acquired infections.